OK, addressed by altering all Text fields in layout designer to be able to store '\1' prefix for Qtf text.
Therefore you can now use any QTF in tooltip, just prepend the text with '\1'. Holds true for other labels as well, e.g. you can now easily use QTF for Button label in layout designer.
Unfortunately, change is too spread across sources, therefore I cannot provide the quick patch here - you have to wait day or two until rc2 is released.